Sound-box diaphragm for use in telephones, loud speakers, acoustic apparatus, and the like



March 22 1927.

SOUND BOX DIAPHRAGM FOR'USE IN TELEPHONES ACOUSTIC APPARATUS, AND THE LIKE Filed Oct. 1, 1924 Patented Mar.19 27.- I n 1,621,670

UNITED STATES PATENT OFFICE.

rmmz JoxEL, or BEEm'mpEmrm, ASSIGNOB 'ro cam. nuns-rubs: AK'IIENGE- 'SELLSGHAFT, or BERLIN, oEamY.

Eon-USE m rEL rnoNEs, 1.01m SPEAKERS, ACOUSTIC arraaa'ros, AND 'rnE LIKE.

SOUND-BOX DIAPHRAGM Application me d October 1, 1924, Serial No. 741,021, and in Germany Kay 1 1924.

This invention relatesto sound box dia- Jmade of some elastic material may be pro phragms for use in telephones, loud speakvided at the outer periphery of the flange. ers, acoustiea paratus and the like, and has The hollow truncated cone shaped ring itparticular' re erence" ,to arrangements for self may be wholly or partially split so as tensioning the diaphragm in such-apparatus: to produce particularly in the case of very It is well known to stretch sound box dialarge diaphragms, an increased tensioning phragms radially; particularly those to be etfect, or the said ring may consist of several used for telephones and loud speakers, soppaj-rts. v I that as thin a material as possible may be In order 'that the said invention may be used for the diaphragm in order to proposed to stretch diap'hra-gms of this kind fully with reference to the examples illllSfby pressing" them through a ring into'an -trated inthe accompanying-drawings, in

"of an elastic pressure ring having the form sure ring d, which is made in the form of a.

annular groove of angular shape in cross sec- Which 2Q tion. The disadvantages of this'f a-rrangement are however the disturbing effect on Inent in accordance with the present inven- -the condition of the material that' is protloil,

duced and the unequal strain put upon the upper and under sides of the diaphragm in ring of a modified form of construction, the inner zoneintended for thetra'nsmission r F1gure 3 1s a vertical section of a further of the sound, with'the result that the diaconstructional form. phragm becomes unevenly stretched. r

The present invention has for its object the diaphragm a which is preferably made to avoidQth e disadvantages above referred of sheet iron is provided with a flanged to,- and for this purpose there is employed g band is m un ed in the Well known in accordance with the invention a device in way onthe base or'foundation plate 0. The which the diaphragm is stretched by means lower and wider edge e of the thrust or presof a hollow truncated cone pressed against hollow truncated cone, is mounted on the the said diaphragm so that the diaphragm other side of the diaphragm. On the upper is held fiat over the whole of its surface by supporting part of the pressure ring d is acting directly against the stretching ring.

the radial pressure of the said ring. For subjecting the *elastic pressure ring to the the screws g and h, which engage in the desired pressure so as to press it against the base or foundation plate 0,- can be adjusted diaphragm there may be employed a thrust 'or clamped fast. B adjusting the screws g plate provided with means such as screws or and h the thrust p ate 7 is pressed against the like forv adjusting its pressure. When the pressure ring d and presses this ring, the diaphragm is to be stretched under very which. owing to its shape is elastic, down high tensions the arrangement'may be such on to -the'd1aphragm a, so that this latter that the pressure ring is stretchedby' means isstretched by the pressurejof the edge e of a stretching ring of wedge-shaped cross of the ring (1 acting in a radial direction. section which engages with the inner sur- Under a suitably hlgh pressure the edge 0 face of the said pressure ring, the said-jot the ring d will bear against the flanged stretching ring being subjected ,either to the edge I) of the diaphragm and produce .a pressure of a thrust plate, provided with further stretching thereof. By suitable adscrews or the like foradjusting its pressure, justment of the screws gan l h it is possible or to the pressure of adjusting screws alone to adjust the pressure of the ring and consequently the stretching of-the diaphragm ,The diaphragm may be provided at its to any 'desired'degree. .edge with a flange, a turned up edge or the like which acts as an abutment for the hol; sure ring may also with 'one or low truncated cone shaped ring. i more radial slits-k as shown 'in Fi In order to prevent the flanged edgeof the which slits are provided at a suitable disdiaphragm from being bent up an abutment tance-from the lower bearing surface of the roduce clearlyunderstood and readily carried into the mass inertia. It has previously been effect, the same will now be described more In the construction shown in Figure 1 laid a thrust plate 7 which, by means'iof In the case of larg: giligliiggms the presi Figure 1 is a cross section of one arrangering. A ring in the formof 'a'hollow fruse tum of a cone compcgsed of a number of parts combined together may also be used.

The constructional form shown in Figure I 3 is specially suitable for arrangements for the production of very highly stretched die;

' phragms, and differs from the constructional structional form shown in Figure 1) with a flanged edge I) and is mounted in-the well known way on a baseor foundation plate 0.

The pressure ring '0 may be wholly or partially slit at 1 or some other suitable point the inner peri hery of t e flange b.

in order to ive" it the required elast1city,

and bears wit its outer erlphery m a ainiz n 1 inner side of t e ressure ring v may be conveniently bevelled off as atm, and .with this bevel thewedge-shaped outer surface 12 of the stretching ring 0 coactsu As shown in Fi re 3 the stretching ring a maybe mounte on a cover plate 1' con structed in the form of a thrust plate. The adjustment or shifting ringo and the thrust plate r is effected by a means of the screws 8, t or the like-of which.

asuitable numherare provided and which are carried in the base or foundation plate 0. .The thrust and pressure later-might be'dispensed with entirely w en adjusting screws acting directly. a ainst the stretchring ring o are The stretching -ring may also;

stretching pieces. On the outer perlphery of the flange b of; the diaphragm there is. provided an abutment u consisting of some elastic material, for-example-fibre or the like, which on its other side bears against the comer plate 1 so that even when the flange b is subjected to severe strain it will be prevented from'bending up without the radial expansion of.the dia hragm when stretched being interferred 'wlth." Sueh an arrangement of elastic abutment may. also @be provided in the ltaonstructibnal- "form shown in Figure 1. I 3

Having now fully described my invention what I claim and des ire to protectby Let- -ters Patent of the United States of America ,1, In a sound box the combination of a base having an opening a diaphragm onthe base and covering-the opening and provided with a peripheral flange, an, elastic pressure ring on the diaphragm and bearing against theflange thereof and means exerting pressure on said'ring to cause it to expan of the stretching fipvide replaced" by separate plate to the base.

dially and thereby exert corresponding pres isiure on the diaphragm and hold the same the flange thereof and means exertingpressure u said'ring to cause it to expand radially andthereby exert correspondingpressure on the diaphragm and hold the same flat, said means including a thrust plate and screws connecting 'the thrust plate to the base, said thrust plate having an opening substantially concentric with that of the base.

base havihgan opening, a diaphragmpn said base covering said openingand havlng 3. In a sound box the combination of a a peripheral flange, an.elastic pressure ring on said diaphragm engaging said flange and having an inclined downwardly converging surface, a stretchin ring in said pressure ring and having a ownwardly converging outer surface and means exerting pressure on said stretching ring to cause the same to radially expand the pressure ring and thereby hold the diaphragm fla't. 4.--In a sound box the combination of a base having an opening, a daphragmon said base covering said opening .and having a pcripheral flange, an elastic pressure ring on said diaphragm ngaging'said flange and living an inclined downwardly converging s rface, a stretchingring in said pressure ring and having a downwardly converging outer surface and means exerting pressure on said stretching ring to cause the same to radially expand the pressure ring and thereby hold the diaphragm flat; said means com prising a thrust plate bearing on" the stretchmg ring and screws connecting said thrust 5. In a-sound box the combination of a base having an opening, a diaphragm on said base covering said opening and having a peripheral flange, an elastic pressure ring on said dlaphragm engaging said flange and having an inclined downwardly converging surface, a stretching ring in said pressure ring and having 1 a downwardly converging.

outer surface-and means'exerting pressure on said stretching ring to cause the same to radially expand the pressure ring and thereby hold the diaphragm flat, said means comprising a thrust plate bearing on 4 V the stretching ring and screws connecting said thrust plate to the base, said thrust plate having a downwardly turnedflange, and an abutment element of elastic material arranged between the flange of the diaphragm andihe flange of the thrust plate.

In testlmony whereof, I aflix my signature. FRANZ JOKELQ 

